This invention generally relates to electrical signalling systems and more specifically to a single wire signalling scheme for vehicle condition monitoring devices wherein power for the device is transmitted to and detection signals are received from the remotely located device using the single wire with ground return through the vehicle frame.
In recent years the number of auxiliary electrical devices marketed for vehicle use has dramatically increased. Among these are electronic apparatus for monitoring all phases of vehicle operation. Past practice has been to design apparatus that may be installed on or adpated to any type vehicle and thus marketed as optional equipment. Presently, however, vehicle manufacturers have increased the number of hazard warning and/or condition monitoring devices that are installed as original equipment . Whether original or optional equipment, the installation poses a problem in that wiring must be provided such that power may be made available for device operation and the signals indicative of a particular condition occurrence may be transmitted back to the operator and timely action taken.
It is thus an object of this invention to simplify and reduce the costs of installing auxiliary devices by providing apparatus for single wire transmission of power to and detection signals from remotely located devices.